dkopitsa/django-permission

An enhanced permission system which support object permission in Django

django-permission

Author

Alisue <lambdalisue@hashnote.net>

Supported python versions

Python 2.7, 3.3, 3.4, 3.5, 3.6

Supported django versions

Django 1.8 - 1.11b

An enhanced permission library which enables a logic-based permission system to handle complex permissions in Django.

Documentation

http://django-permission.readthedocs.org/en/latest/

Installation

Use pip like:

$ pip install django-permission

Usage

The following might help you to understand as well.

• Basic strategy or so on, Issue #28
• Advanced usage and examples, Issue #26

Configuration

1. Add permission to the INSTALLED_APPS in your settings module

   INSTALLED_APPS = (
       # ...
       'permission',
   )

2. Add our extra authorization/authentication backend

   AUTHENTICATION_BACKENDS = (
       'django.contrib.auth.backends.ModelBackend', # default
       'permission.backends.PermissionBackend',
   )

3. Follow the instructions below to apply logical permissions to django models

Autodiscovery

Like django's admin package, django-permission automatically discovers the perms.py in your application directory by running ``permission.autodiscover()``. Additionally, if the perms.py module has a PERMISSION_LOGICS variable, django-permission automatically run the following functions to apply the permission logics.

for model, permission_logic_instance in PERMISSION_LOGICS:
    if isinstance(model, str):
        model = get_model(*model.split(".", 1))
    add_permission_logic(model, permission_logic_instance)

Note

Autodiscover feature is automatically called if you are using django higher than 1.7 so no need to follow the tutorial below. To disable, use PERMISSION_AUTODISCOVER_ENABLE setting.

Quick tutorial

1. Add import permission; permission.autodiscover() to your urls.py like:

   from django.conf.urls import patterns, include, url
   from django.contrib import admin
   
   admin.autodiscover()
   # add this line
   import permission; permission.autodiscover()
   
   urlpatterns = patterns('',
       url(r'^admin/', include(admin.site.urls)),
       # ...
   )

2. Write perms.py in your application directory like:

   from permission.logics import AuthorPermissionLogic
   from permission.logics import CollaboratorsPermissionLogic
   
   PERMISSION_LOGICS = (
       ('your_app.Article', AuthorPermissionLogic()),
       ('your_app.Article', CollaboratorsPermissionLogic()),
   )

You can specify a different module or variable name, with PERMISSION_AUTODISCOVER_MODULE_NAME or PERMISSION_AUTODISCOVER_VARIABLE_NAME respectively.

Apply permission logic

Let's assume you wrote an article model which has an author attribute to store the creator of the article, and you want to give that author full control permissions (e.g. add, change and delete permissions).

What you need to do is just applying permission.logics.AuthorPermissionLogic to the Article model like

from django.db import models
from django.contrib.auth.models import User


class Article(models.Model):
    title = models.CharField('title', max_length=120)
    body = models.TextField('body')
    author = models.ForeignKey(User)

    # this is just required for easy explanation
    class Meta:
        app_label='permission'

# apply AuthorPermissionLogic
from permission import add_permission_logic
from permission.logics import AuthorPermissionLogic
add_permission_logic(Article, AuthorPermissionLogic())

Note

From django-permission version 0.8.0, you can specify related object with field__name attribute like django queryset lookup. See the working example below:

from django.db import models
from django.contrib.auth.models import User


class Article(models.Model):
    title = models.CharField('title', max_length=120)
    body = models.TextField('body')
    project = models.ForeignKey('permission.Project')

    # this is just required for easy explanation
    class Meta:
        app_label='permission'

class Project(models.Model):
    title = models.CharField('title', max_length=120)
    body = models.TextField('body')
    author = models.ForeignKey(User)

    # this is just required for easy explanation
    class Meta:
        app_label='permission'

# apply AuthorPermissionLogic to Article
from permission import add_permission_logic
from permission.logics import AuthorPermissionLogic
add_permission_logic(Article, AuthorPermissionLogic(
    field_name='project__author',
))

That's it. Now the following codes will work as expected:

user1 = User.objects.create_user(
    username='john',
    email='john@test.com',
    password='password',
)
user2 = User.objects.create_user(
    username='alice',
    email='alice@test.com',
    password='password',
)

art1 = Article.objects.create(
    title="Article 1",
    body="foobar hogehoge",
    author=user1
)
art2 = Article.objects.create(
    title="Article 2",
    body="foobar hogehoge",
    author=user2
)

# You have to apply 'permission.add_article' to users manually because it
# is not an object permission.
from permission.utils.permissions import perm_to_permission
user1.user_permissions.add(perm_to_permission('permission.add_article'))

assert user1.has_perm('permission.add_article') == True
assert user1.has_perm('permission.change_article') == False
assert user1.has_perm('permission.change_article', art1) == True
assert user1.has_perm('permission.change_article', art2) == False

assert user2.has_perm('permission.add_article') == False
assert user2.has_perm('permission.delete_article') == False
assert user2.has_perm('permission.delete_article', art1) == False
assert user2.has_perm('permission.delete_article', art2) == True

#
# You may also be interested in django signals to apply 'add' permissions to the
# newly created users.
# https://docs.djangoproject.com/en/dev/ref/signals/#django.db.models.signals.post_save
#
from django.db.models.signals.post_save
from django.dispatch import receiver
from permission.utils.permissions import perm_to_permission

@receiver(post_save, sender=User)
def apply_permissions_to_new_user(sender, instance, created, **kwargs):
    if not created:
        return
    #
    # permissions you want to apply to the newly created user
    # YOU SHOULD NOT APPLY PERMISSIONS EXCEPT PERMISSIONS FOR 'ADD'
    # in this way, the applied permissions are not object permission so
    # if you apply 'permission.change_article' then the user can change
    # any article object.
    #
    permissions = [
        'permission.add_article',
    ]
    for permission in permissions:
        # apply permission
        # perm_to_permission is a utility to convert string permission
        # to permission instance.
        instance.user_permissions.add(perm_to_permission(permission))

See http://django-permission.readthedocs.org/en/latest/_modules/permission/logics/author.html#AuthorPermissionLogic to learn how this logic works.

Now, assume you add collaborators attribute to store collaborators of the article and you want to give them a change permission.

What you need to do is quite simple. Apply permission.logics.CollaboratorsPermissionLogic to the Article model as follows

from django.db import models
from django.contrib.auth.models import User


class Article(models.Model):
    title = models.CharField('title', max_length=120)
    body = models.TextField('body')
    author = models.ForeignKey(User)
    collaborators = models.ManyToManyField(User)

    # this is just required for easy explanation
    class Meta:
        app_label='permission'

# apply AuthorPermissionLogic and CollaboratorsPermissionLogic
from permission import add_permission_logic
from permission.logics import AuthorPermissionLogic
from permission.logics import CollaboratorsPermissionLogic
add_permission_logic(Article, AuthorPermissionLogic())
add_permission_logic(Article, CollaboratorsPermissionLogic(
    field_name='collaborators',
    any_permission=False,
    change_permission=True,
    delete_permission=False,
))

Note

From django-permission version 0.8.0, you can specify related object with field_name attribute like django queryset lookup. See the working example below:

from django.db import models
from django.contrib.auth.models import User


class Article(models.Model):
    title = models.CharField('title', max_length=120)
    body = models.TextField('body')
    project = models.ForeignKey('permission.Project')

    # this is just required for easy explanation
    class Meta:
        app_label='permission'

class Project(models.Model):
    title = models.CharField('title', max_length=120)
    body = models.TextField('body')
    collaborators = models.ManyToManyField(User)

    # this is just required for easy explanation
    class Meta:
        app_label='permission'

# apply AuthorPermissionLogic to Article
from permission import add_permission_logic
from permission.logics import CollaboratorsPermissionLogic
add_permission_logic(Article, CollaboratorsPermissionLogic(
    field_name='project__collaborators',
))

That's it. Now the following codes will work as expected:

user1 = User.objects.create_user(
    username='john',
    email='john@test.com',
    password='password',
)
user2 = User.objects.create_user(
    username='alice',
    email='alice@test.com',
    password='password',
)

art1 = Article.objects.create(
    title="Article 1",
    body="foobar hogehoge",
    author=user1
)
art1.collaborators.add(user2)

assert user1.has_perm('permission.change_article') == False
assert user1.has_perm('permission.change_article', art1) == True
assert user1.has_perm('permission.delete_article', art1) == True

assert user2.has_perm('permission.change_article') == False
assert user2.has_perm('permission.change_article', art1) == True
assert user2.has_perm('permission.delete_article', art1) == False

See http://django-permission.readthedocs.org/en/latest/_modules/permission/logics/collaborators.html#CollaboratorsPermissionLogic to learn how this logic works.

There are StaffPermissionLogic and GroupInPermissionLogic for is_staff or group based permission logic as well.

Customize permission logic

Your own permission logic class must be a subclass of permission.logics.PermissionLogic and must override has_perm(user_obj, perm, obj=None) method which return boolean value.

Class, method, or function decorator

Like Django's permission_required but it can be used for object permissions and as a class, method, or function decorator. Also, you don't need to specify a object to this decorator for object permission. This decorator automatically determined the object from request (so you cannnot use this decorator for non view class/method/function but you anyway use user.has_perm in that case).

>>> from permission.decorators import permission_required
>>> # As class decorator
>>> @permission_required('auth.change_user')
>>> class UpdateAuthUserView(UpdateView):
...     pass
>>> # As method decorator
>>> class UpdateAuthUserView(UpdateView):
...     @permission_required('auth.change_user')
...     def dispatch(self, request, *args, **kwargs):
...         pass
>>> # As function decorator
>>> @permission_required('auth.change_user')
>>> def update_auth_user(request, *args, **kwargs):
...     pass

Override the builtin if template tag

django-permission overrides the builtin if tag, adding two operators to handle permissions in templates. You can write a permission test by using has keyword, and a target object with of as below.

{% if user has 'blogs.add_article' %}
    <p>This user have 'blogs.add_article' permission</p>
{% elif user has 'blog.change_article' of object %}
    <p>This user have 'blogs.change_article' permission of {{object}}</p>
{% endif %}

{# If you set 'PERMISSION_REPLACE_BUILTIN_IF = False' in settings #}
{% permission user has 'blogs.add_article' %}
    <p>This user have 'blogs.add_article' permission</p>
{% elpermission user has 'blog.change_article' of object %}
    <p>This user have 'blogs.change_article' permission of {{object}}</p>
{% endpermission %}

Note

From Django 1.9, users require to add 'permission.templatetags.permissionif' to 'builtins' option manually. See - https://docs.djangoproject.com/en/1.9/releases/1.9/#django-template-base-add-to-builtins-is-removed - https://docs.djangoproject.com/en/1.9/topics/templates/#module-django.template.backends.django Or following example:

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'OPTIONS': {
            'builtins': ['permission.templatetags.permissionif'],
        },
    },
]

License

The MIT License (MIT)

Copyright (c) 2015 Alisue, hashnote.net

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.